Pollen-induced airway inflammation, hyper-responsiveness and apoptosis in a murine model of allergy

Aerofloral studies and allergenicity of dominant pollen types in Taraba and Bauchi States of Northeastern Nigeria

Pollen and spores have been identified as major airborne bio-particles inducing respiratory disorders including allergic rhinitis and atopic dermatitis among hypersensitive individuals. The present study was conducted with a view to investigating monthly depositional rate of atmospheric palynomorphs to determine the influence of the immediate vegetation on airborne pollen distribution; allergenic activities of dominant atmospheric pollen types at selected study locations in Taraba and Bauchi States, Northeastern Nigeria. Bioaerosols were collected using Tauber-like pollen traps and subjected to standard palynological treatment procedures, microscopy and photomicrography. Plant enumeration within the surrounding vegetation revealed that some airborne pollen types were produced by local plants at the study locations. Spores of Nephrolepis sp., Pteris sp. and a trilete fern, as well as diatoms were also recovered. Crude protein contents of some dominant pollen types; Borreria verticillata (L.) G.F.W. Meyer and Panicum maximum Jacq. for Taraba State; Leucaena leucocephala (Lam.) de Wit. and Terminalia catappa L. for Bauchi State, were quantified and extracted to sensitize Mus musculus mice for serology (ELISA) and haematology (differential and total white blood cell counts). Statistical significance was tested and recorded in the correlation between levels of serological and haematological parameters elicited by each test group; differences between levels of these parameters elicited by each test group and those of the control, as well as at varying sensitization periods. In the Leucaena leucocephala test group, swollen body and histopathological morbid features showing more extensive areas of inflammatory cells and alveoli filled with fluid in the lungs, were recorded in two dead M. musculus, respectively. The study revealed that all the tested pollen types are possible allergens at the study locations, establishing a complexity of interaction among allergy mediators at varied periods of mice sensitization and forming a paradigm of human immune response to the different pollen allergens.

Establishment and characterization of murine models of asthma and subcutaneous immunotherapy for Humulus pollen allergy

Introduction

Humulus pollen is an important cause of allergic asthma in East Asia. There have been some murine models for Humulus pollen allergy established by intraperitoneal (IP) sensitization and nasal drip stimulation, but they were not comprehensive enough. Here, we used atomized inhalation for challenge and compared the subcutaneous (SC) and IP sensitization routes to determine the optimal method to establish a model of asthma induced by Humulus pollen. Subsequently, we tried to develop a rapid subcutaneous immunotherapy (SCIT) model for Humulus allergy.

Methods

BALB/c Mice were sensitized through the SC or IP route, with respective reference to previously established sensitization methods and allergen dosing, and challenged with nebulized Humulus pollen extract to induce asthma. To compare the two sensitization methods, airway hyperresponsiveness (AHR), inflammatory cell infiltration, allergen‐specific serum immunoglobulin (Ig)E (sIgE) levels, cytokine levels, and lung histopathology were assessed. The effects of SCIT (once every other day for 16 days) on airway inflammation, AHR, sIgE, and allergen‐specific serum IgG2a (sIgG2a) levels were evaluated by using the model established in this study.

Results

Although mice sensitized by the SC or IP routes both showed AHR and airway inflammation, the SC route elicited significantly higher levels of sIgE, eosinophil inflammation, and T helper type 2 cytokines, compared with the IP route. SCIT in the treatment group significantly reduced the titers of sIgE, enhanced the titers of sIgG2a, and effectively alleviated pulmonary inflammation and AHR, compared with the vehicle group.

Conclusions

The SC route can be used to establish a murine model of Humulus pollen allergy that recapitulates the characteristics of clinical allergic asthma. Short‐term SCIT can significantly improve symptoms and pathophysiology in asthmatic mice.

Specific panallergen peptide of Sorghum Polcalcin showing IgE response identified based on in silico and in vivo peptide mapping

In India, Sorghum plant allergenicity was reported to be approximately 54.9%. Sorghum bicolor Polcalcin (Sorb PC) was identified as the panallergen but the specificity of this allergen is yet to be characterized. The present study was aimed to characterize the antigenic determinants of Sorb PC that are responsible for eliciting the IgE response. In silico modeling, simulation studies and docking of Sorb PC peptides (PC1-11) against IgG and IgE followed by in vivo evaluation was adopted. Peptide docking studies revealed PC 6 with highest G-score -12.85 against IgE followed by PC-11, 5, 1 and 7 (-10.91) peptides. The mice sensitized with PC7 peptide showed interleukin (IL) 4 (IL-4), IL-5, IL-12, TNF-α and GMCSF levels increased when compared with other peptides and controls, signifying a strong T helper type 2 (Th2)-based response. In tandem, the T helper type 1 (Th1) pathway was inhibited by low levels of cytokine IL-2, interferon γ (IFN-γ) and increased IL-10 levels justifying the role of PC7 in allergic IgE response. Considering the above data of overlapping peptides of PC6 and PC7, N-terminal part of the PC7 peptide (DEVQRMM) is found to play a crucial role in Sorghum Polcalcin allergenic response.

Peptide Mapping, In Silico and In Vivo Analysis of Allergenic Sorghum Profilin Peptides

Background and objectives: Nearly 20–30% of the world’s population suffers from allergic rhinitis, among them 15% are progressing to asthma conditions. Sorghum bicolor profilin (Sorb PF), one of the panallergens, was identified, but the allergen specificity is not yet characterized. Materials and Methods: To map the antigenic determinants responsible for IgE binding, the present study is focused on in silico modeling, simulation of Sorb PF and docking of the Sorb PF peptides (PF1-6) against IgG and IgE, followed by in vivo evaluation of the peptides for its allergenicity in mice. Results: Peptide PF3 and PF4 displayed high docking G-scores (−9.05) against IgE only. The mice sensitized with PF3 peptide showed increased levels of IL5, IL12, TNF-alpha, and GMCSF when compared to other peptides and controls, signifying a strong, Th2-based response. Concurrently, the Th1 pathway was inhibited by low levels of cytokine IL2, IFN-γ, and IL-10 justifying the role of PF3 in allergenic IgE response. Conclusions: Based on the results of overlapping peptides PF3 and PF4, the N-terminal part of the PF3 peptide (TGQALVI) plays a crucial role in allergenic response of Sorghum profilin.

IgE-mediated allergic responses associated to Ailanthus altissima pollen using an animal model

BACKGROUND

Murine models have been widely used in the study of allergy as sensitized mice can produce IgE and/or IgG1in response after the injection of an antigen/adjuvant combination. Ailanthus altissima pollen (AAP) has been recently reported as an emerging aeroallergen in Iran. So far, several AAP candidate allergens by the screening of allergen-specific IgE in the sera from AAP sensitized patients in Iran.

OBJECTIVE

The aim of the present study was to detect and compare the allergens eliciting an IgE response in a mouse model, and in human, using pollen extract of A. altissima and an immunoproteomics based approach.

METHODS

The pollen proteins were extracted in phosphate-buffered saline (PBS). Thirty male BALB/c mice were randomly divided into two groups of AP extract sensitized and sham that respectively received AAP PBS extract and a PBS control by intraperitoneal injections at regular intervals. The optimized AAP protein extracts were analyzed using 2D-gel electrophoresis and were subsequently confronted to pooled sera of sensitized mice.

RESULTS

Two-D gel electrophoresis of AAP extract allowed the separation of 125 protein spots distributed in a wide range of pI and molecular masses. Two-DE immunoblotting using pooled sera of sensitized mice led to the detection of 14 IgE reactive spots with molecular masses ranging from 12 to 40-42kDa.

CONCLUSION

The results do not correlate with our previous analyses using human AAP-sensitized sera. These findings reflect some differences in the sIgE reactivity to allergenic proteins in animal models.

Comparative study of adjuvants for allergen-specific immunotherapy in a murine model

AIM

To compare the immunological and clinical changes induced by allergen-specific immunotherapy (AIT) using different adjuvants.

MATERIALS & METHODS

Olea europaea pollen-sensitized mice were treated with olea plus aluminum hydroxide, calcium phosphate, monophosphoryl lipid A (MPL) or immunostimulatory sequences (ISS).

RESULTS

Aluminum hydroxide seems to drive initially to a Th2-type response. Bacteria-derived adjuvants (MPL and ISS) skew the immune response toward Th1 and Treg pathways. Specific-IgE production was lower after AIT with MPL and ISS. Moreover, IgG2a production significantly increased in ISS-treated mice. Bacteria-derived adjuvants also improved the Th1 cytokine response due to IFN-γ higher secretion. In addition, they improved bronchial hyper-reactivity and lung inflammation.

CONCLUSION

Bacteria-derived adjuvants may enhance the efficacy of AIT.

Antibacterial activities of medicinal plants used in Mexican traditional medicine

ETHNOPHARMACOLOGICAL RELEVANCE

We provide an extensive summary of the in vitro antibacterial properties of medicinal plants popularly used in Mexico to treat infections, and we discuss the ethnomedical information that has been published for these species.

MATERIALS AND METHODS

We carried out a bibliographic investigation by analyzing local and international peer-reviewed papers selected by consulting internationally accepted scientific databases from 1995 to 2014. We provide specific information about the evaluated plant parts, the type of extracts, the tested bacterial strains, and the inhibitory concentrations for each one of the species. We recorded the ethnomedical information for the active species, as well as their popular names and local distribution. Information about the plant compounds that has been identified is included in the manuscript. This review also incorporates an extensive summary of the available toxicological reports on the recorded species, as well as the worldwide registries of plant patents used for treating bacterial infections. In addition, we provide a list with the top plant species with antibacterial activities in this review RESULTS: We documented the in vitro antibacterial activities of 343 plant species pertaining to 92 botanical families against 72 bacterial species, focusing particularly on Staphylococcus aureus, Mycobacterium tuberculosis, Escherichia coli and Pseudomonas aeruginosa. The plant families Asteraceae, Fabaceae, Lamiaceae and Euphorbiaceae included the largest number of active species. Information related to popular uses reveals that the majority of the plants, in addition to treating infections, are used to treat other conditions. The distribution of Mexican plants extended from those that were reported to grow in just one state to those that grow in all 32 Mexican states. From 75 plant species, 225 compounds were identified. Out of the total plant species, only 140 (40.57%) had at least one report about their toxic effects. From 1994 to July 2014 a total of 11,836 worldwide antibacterial patents prepared from different sources were recorded; only 36 antibacterial patents from plants were registered over the same time period. We offered some insights on the most important findings regarding the antibacterial effects, current state of the art, and research perspectives of top plant species with antibacterial activities in vitro.

CONCLUSIONS

Studies of the antibacterial in vitro activity of medicinal plants popularly used in Mexico to treat infections indicate that both the selection of plant material and the investigation methodologies vary. Standardized experimental procedures as well as in vivo pharmacokinetic studies to document the effectiveness of plant extracts and compounds are necessary. This review presents extensive information about the medicinal plants possessing antibacterial activity that has been scientifically studied and are popularly used in Mexico. We anticipate that this review will be of use for future studies because it constitutes a valuable information tool for selecting the most significant plants and their potential antibacterial properties.

General and Specific Mouse Models for Asthma Research

To study the complexity of human asthma disease, the development of different animal models is needed. Among all different laboratory animals, mice represent a useful tool for the development of asthma. This chapter will describe protocols for designing different animal models applied to the studying of asthma phenotypes.

Specific allergen immunotherapy attenuates allergic airway inflammation in a rat model of Alstonia scholaris pollen induced airway allergy

Pollen grains are well established to be an important cause of respiratory allergy. Current pharmacologic therapies for allergic asthma do not cure the disease. Allergen specific immunotherapy is the only treatment method which re-directs the immune system away from allergic response leading to a long lasting effect. The mechanism by which immunotherapy achieves this goal is an area of active research world-wide. The present experimental study was designed to develop an experimental model of allergic lung inflammation based on a relevant human allergen, Alstonia scholaris pollen, and to establish the immunological and cellular features of specific allergen immunotherapy using this same pollen extract. Our results revealed that Alstonia scholaris pollen sensitization and challenge causes eosinophilic airway inflammation with mucin hypersecretion. This is associated with increased total IgE, increased expression of FcɛRI on lung mast cells and increased levels of IL-4, IL-5 & IL-13 as confirmed by ELISA, in-situ immunofluorescence and FACS assay. Allergen specific immunotherapy reduced airway inflammation and also decreased total IgE level, FcɛRI expression, IL-4, IL-5 & IL-13 levels. It was further noted that the reduction of these levels was more by intra-nasal route than by intra-peritoneal route. Thus we present a novel animal model of Alstonia scholaris pollen allergic disease and specific allergen immunotherapy which will pave the way towards the development of better treatment modalities.

Epicutaneous Immunotherapy Compared with Sublingual Immunotherapy in Mice Sensitized to Pollen (Phleum pratense)

Background. The aim of this study was to compare the efficacy of epicutaneous immunotherapy (EPIT) to sublingual immunotherapy (SLIT) in a model of mice sensitized to Phleum pratense pollen. Methods. BALB/c mice were sensitized by sub-cutaneous route to pollen protein extract mixed treated for 8 weeks, using sham, EPIT, or SLIT. Measurements involved the serological response and cytokine profile from reactivated splenocytes, plethysmography after aerosol challenge to pollen, cell, and cytokine contents in the bronchoalveolar lavages (BALs). Results. After immunotherapy, sIgE was significantly decreased in the treated groups compared to sham (P < 0.001), whereas sIgG2a increased with EPIT and SLIT (P < 0.001 and P < 0.005 versus sham). Reactivated splenocytes secreted higher levels of Th2 cytokines with sham (P < 0.01). Penh values were higher in sham than EPIT and SLIT. Eosinophil recruitment in BAL was significantly reduced only by EPIT (P < 0.01). Conclusion. In this model of mice sensitized to pollen, EPIT was at least as efficient as SLIT.

Transforming growth factor beta: a role in the upper airway and rhinosinusitis-Dermatophagoides pteronyssinus-induced apoptosis with pulmonary alveolar cells

BACKGROUND

There is a link with the upper and lower airway and disruption of alveolar epithelial cells, which is a potential trigger for the reactivation of the epithelial-mesenchymal trophic unit (EMTU) and induced characteristic airway changes associated with allergic asthma. Dermatophagoides pteronyssinus is a common inhalant indoor allergen and is known for causing allergic rhinitis and airway inflammation. Transforming growth factor beta 1 (TGF-beta1) is a major participant in the airway remodeling of asthma, a component of cellular stress response pathways, and enhanced epithelial immunoreactivity is known to occur in allergic rhinitis.

METHODS

In this study, we show the ability of D. pteronyssinus allergens from dialyzed standardized immunotherapy extract to induce apoptosis and increase TGF-beta1 secretion in a confluent A549 cell line model. A549 cells were treated with either 600 AU/mL dialyzed D. pteronyssinus immunotherapy extract (eDp) or Ctl media (Ctl) for 24 hours. Cells and supernatants were collected, washed, and treated with Annexin V-FITC Apoptosis Detection Kit II (BD Pharmingen, La Jolla, CA) and then analyzed by flow cytometry. TGF-beta1 secretion was determined by ELISA using cell culture supernatants.

RESULTS

The eDp group showed a fourfold increase in early apoptotic cells with a twofold increase in late apoptotic cells versus the Ctl group, along with a 1.65-fold increase of TGF-beta1.

CONCLUSION

eDp induced viable A549 cells to undergo apoptosis determined by flow cytometry analysis with a significant increase in TGF-beta1 secretion compared with Ctl.

Epicutaneous immunotherapy on intact skin using a new delivery system in a murine model of allergy

BACKGROUND

Allergen-specific immunotherapy, subcutaneous immunotherapy (SCIT) or oral, has been used for almost a century to redirect inappropriate immune responses in atopic patients. A new mode of administration through the intact skin [epicutaneous immunotherapy (EPIT)], using an original epicutaneous delivery system, may represent an alternative to these classical methods.

OBJECTIVE

Proof of concept of efficacy of EPIT on intact skin in mice sensitized to aeroallergens or food allergens.

METHODS

Mice were sensitized to pollen (n=18), house dust mite (HDM, n=24), ovalbumin (OVA, n=18) or peanut (n=18), and allocated to four groups: EPIT, SCIT, not treated (NT) and control. Specific Ig (sIg)E, sIgG1 and sIgG2a were monitored. After 8 weeks of treatment, plethysmography was performed after aerosol provocation with appropriate allergens.

RESULTS

At the highest doses of methacholine, pause enhancement (Penh) values were significantly decreased in the EPIT group vs. the sensitized NT groups (7.5 vs. 12.3 - pollen, 7.6 vs. 8.9 - HDM, 11.5 vs. 14.5 - OVA, 7.6 vs. 12.8 - peanut, respectively) (P<0.05). With all the allergens tested, Penh values were similar in SCIT, EPIT and control. IgG2a for pollen, HDM, OVA and peanuts were significantly increased in the EPIT group vs. NT: 0.97 vs. 0.42 microg/mL, 2.5 vs. 0.46 microg/mL, 0.39 vs. 0.05 microg/mL and 15.0 vs. 5.5 microg/mL, respectively (P<0.05). There were no significant differences between EPIT and SCIT groups. The IgE/IgG2a ratio decreased significantly in the EPIT group for the four allergens from 70 to 58 (pollen), 175 to 26 (HDM), 5433 to 120 (OVA) and 49 to 6 (peanut), respectively (P<0.05).

CONCLUSION

In mice sensitized to the four allergens tested, EPIT was as efficacious as SCIT, considered as the reference immunotherapy. These first results have to be confirmed by clinical studies.

Impact on allergic immune response after treatment with vitamin A

BACKGROUND

Vitamin A may have some influence on the immune system, but the role in allergy modulation is still unclear.

OBJECTIVE

To clarify whether high levels of retinoic acid (RA) affects allergic response in vivo, we used a murine experimental model of airway allergic disease.

METHODS

Ovalbumin (OVA)-immunization/OVA-challenge (OVA/OVA) and house dust mite (HDM)-immunization/HDM-challenge (HDM/HDM) experimental murine models of allergic airway disease, using C57Bl.10/Q groups of mice (n = 10) treated subcutaneously with different concentrations of all-trans RA (0, 50, 500 and 2,500 ug) every 2-days were used to assess the allergic immune response.

RESULTS

Levels of total and specific-IgE in sera were increased in all groups of RA treated OVA/OVA and HDM/HDM mice. Percentage and total amount of recruited eosinophil in airways by bronchoalveolar lavage fluid (BALF) were significantly enhanced in groups treated with 50, 500 and 2,500 ug of RA compared to non-treated mice. However, the group of mice treated with 2,500 ug had less eosinophil recruitment than the other two groups (50 and 500 ug). In parallel, levels of IL-5 and total IgE in BALF were also significantly diminished in the group treated with 2,500 ug compared to the other 2 groups (50 and 500 ug). Finally, total lung resistance was decreased in group treated with 2,500 ug compared to non-treated mice.

CONCLUSION

Our results suggest that retinoic acid directly enhances allergic response in vivo, but in higher doses may produce of immune suppression.

Automatic quantification of histological studies in allergic asthma

The evaluation of new therapies to treat allergic asthma makes frequent use of histological studies. Some of them are based on microscope observation of stained paraffin lung sections to quantify cellular infiltrate, an effect directly related to allergic processes. Currently, there is no software tool available for doing this quantification automatically. This paper presents a methodology and a software tool for the quantification of cellular infiltrate in lung tissue images in an allergic asthma mouse model. The image is divided into regions of equal size, which are then classified by means of a segmentation algorithm based on texture analysis. The classification uses three discriminant functions, built from parameters derived from the histogram and the co-occurrence matrix. These functions were calculated by means of a stepwise discriminant analysis on 79 samples from a training set. Results provided a correct classification of 96.8% on an independent test set of 251 samples labeled manually. Regression analysis showed a good agreement between automatic and manual methods. A reliable and easy to implement method has been developed to provide an automatic method for quantifying microscopy images of lung histological studies. Results showed similar accuracy to that provided by an expert, while allowing analyzing a much larger number of fields in a repeatable way.

Assessment of airway distribution of transnasal solutions in mice by PET/CT imaging

PURPOSE

Transnasal administration is one of the most common routes for allergen challenge in mouse models of airway diseases. Although this technique is widely used, neither the amount of allergen that reaches the lung nor its airway distribution has been well established. We used positron emission tomography (PET) and computed tomography (CT) to examine the anatomical distribution of a solution containing a tracer immediately after transnasal delivery and to determine the possible influence of age and administered volume.

PROCEDURES

Forty-six female BALB/c mice were divided into three groups according to instillation volume and age: (A) 15 microl, 8-10 weeks old (N = 10), (B) 30 microl, 8-10 weeks old (N = 20), and (C) 30 microl, 32 weeks old (N = 16). Anesthetized animals underwent a dynamic scan in a dedicated small-animal PET scanner immediately after transnasal administration of a solution containing (18)FDG. Regions of interest were used to obtain quantitative data. Animals were also imaged with a small-animal CT scanner to obtain complementary anatomical information.

RESULTS

Mean +/- SD (5.69 +/- 4.51%) of the solution administered reached the lungs in group A, 41.84 +/- 8.03% in group B, and 36.65 +/- 16.15% in group C. A comparable percentage was delivered to the left and right lungs in all the groups. Analysis of variance revealed a significant difference between the groups in the proportion of the solution that reached the lungs depending on the injection volume (P < 0.001), but not depending on animal age.

CONCLUSIONS

In this first report on quantitative imaging by PET and CT in small animals, we confirmed the suitability of the transnasal route with an instilled volume of 30 microl delivering fluids into the lower airways, although only about 40% of the dose reaches the lungs.